1. Field of the Invention
The present invention relates to an electronic parts packaging structure and a manufacturing method thereof. More particularly, the present invention relates to an electronic parts packaging structure in which an MEMS element and the like are formed while being hermetically sealed with a sealing cap, and a manufacturing method thereof.
2. Description of the Related Art
In the prior art, there is an MEMS (micro-electro-mechanical system) element device having a structure in which an MEMS element is formed on a substrate and is hermetically sealed with a sealing cap. As shown in FIG. 1, in an example of an element substrate of the MEMS element device in the prior art, a coil 102 and a protective layer 104 which covers the coil 102 are formed on a silicon substrate 100. Moreover, a switch element 106 having a movable portion 106a as an MEMS element is an provided on the protective layer 104. An electrode 108 is provided on the protective layer 104 corresponding to one end of the movable portion 106a of the switch element 106. Accordingly, when the movable portion 106a of the switch element 106 comes into contact with the electrode 108, a switch circuit is turned on.
Moreover, an opening 104a is provided in a portion of the protective layer 104 on a periphery part of the silicon substrate 100, and in the opening 104a, the silicon substrate 100 is exposed. Moreover, alignment marks M1 for positioning and disposing a sealing cap to be described later are formed on a peripheral side on the protective layer 104.
Furthermore, as shown in FIG. 2, a sealing cap 110 for hermetically sealing the switch element 106 is prepared, which is made of glass and has a cavity 110a provided in a center portion thereof. The sealing cap 110 also has alignment marks M2 provided in a periphery part of a bottom of the cavity 110a. Specifically, the alignment marks M2 are for disposing the sealing cap 110 to the switch element 106 with alignment condition.
As shown in FIGS. 3 and 4, a peripheral part of the sealing cap 110 is bonded to the peripheral part of the silicon substrate 100 in a state where the cap and the substrate are positioned so as to align and house the switch element 106 in the cavity 110a of the sealing cap 110 by use of an anodic bonding apparatus. In this event, the anodic bonding apparatus includes a recognition camera, and the positioning is performed based on recognition of the alignment marks M1 of the silicon substrate 100 and the alignment marks M2 of the sealing cap 110 by the recognition camera. Thus, the sealing cap 110 is disposed on the silicon substrate 100 and bonded thereto.
As a technology related to a method of manufacturing the MEMS element device as described above, the following technology is described in Patent Document 1 (Japanese Unexamined Patent Publication No. 2005-19966). Specifically, a cap arrayed wafer including a plurality of sealing caps is stuck to a semiconductor wafer having a plurality of MEMS elements provided thereon, thereby MEMS elements are sealed. And then, the wafer is cut to obtain individual packages.
Moreover, the following technology is described in Patent Document 2 (Japanese Unexamined Patent Publication No. Hei 8 (1996)-316496). Specifically, on a silicon wafer having a plurality of function elements provided thereon, another silicon wafer which has a cut formed therein in a state of being stuck to an adhesive sheet, is stuck by a bonding member. Thereby, the function element portion is sealed so as to be surrounded by the bonding member. And then the cut portion is removed and the silicon wafer of the function element side is cut.
Furthermore, the following technology is described in Patent Document 3 (Japanese Unexamined Patent Publication No. 2004-209585). Specifically, a case is bonded to a device main body in which a MEMS element is provided so as to define a hermetically-sealed space by use of ultrasonic bonding.
However, in the above-described method in which the sealing cap 110 is disposed on the silicon substrate 100 on which the MEMS element 106 is formed while aligning the cap with the substrate by use of the recognition camera, a complex and expensive alignment mechanism is required, which includes the recognition camera, software for processing images taken by the camera, and the like. Thus, there is a problem of an increase in manufacturing costs.
Furthermore, in the prior art, it is required to specially form the alignment marks on the silicon substrate 100 and the sealing cap 110. Particularly, in order to form the alignment marks M2 on the sealing cap 110 side, it is required to specially carry out deposition and photolithography. From this viewpoint, also manufacturing costs are increased.